Study on Fe–Si–Cr Soft magnetic composite coated with silicon dioxide

The purpose of this experiment is to explore the effect of SiO₂ coating on the properties of Fe–Si–Cr materials. The suitable surface modifier (CTAB) for this experiment was selected by sol-gel method. And the SiO₂ insulating layer was coated on the surface of Fe–Si–Cr powder by controlling the addition of TEOS and CTAB. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), powder particle size analyzer and scanning electron microscope (SEM) were used to characterize the microstructure, composition and dispersibility of the powder. Soft magnetic AC testing system and soft magnetic DC testing system were used to test the magnetic properties of magnetic ring. The results showed that the surface of Fe–Si–Cr powder was modified by CTAB and then when the ethyl orthosilicate was added, the surface of Fe–Si–Cr powder can be coated with a layer of flocculent amorphous SiO₂; with the increase of ethyl orthosilicate and surface modifier, the SiO₂ coating amount also increased. The magnetic flux density (BM) varies from 0.020 T to 0.025 T, and the coercivity (HC) remains basically unchanged. When 10 ml ethyl orthosilicate and 3 g CTAB were added, the coating effect and performance were the best, with magnetic loss of 4.666 kW m⁻³, magnetic flux density of 0.0248 T and coercive force of 13.87 A m⁻¹. (paper)